In the past, there is known a method of controlling, in a local area network in which a plurality of communication nodes are connected, transmission of data from the communication nodes using a token passing system for circulating a token frame that indicates a transmission right (see, for example, Patent Document 1). In the technology described in Patent Document 1, an allowed transmission data amount, which is an amount of data that can be transmitted while the token frame is circulated in a network once, is set in the token frame and, when an amount of data that should be transmitted by a communication node that has acquired the token frame is equal to or smaller than the allowed transmission data amount set in the token frame, after the data is transmitted, a token frame in which an amount of data obtained by subtracting the transmitted amount of data from the allowed transmission data amount is set as a new allowed transmission data amount is transmitted to the next communication node. When the amount of data that should be transmitted is larger than the allowed transmission data amount, the communication node transmits a token frame in which the allowed transmission data amount is set to 0 to the next node and memorizes that the allowed transmission data amount is set to 0. Even if communication nodes having turns of token circulation order after the turn of this communication node acquire the token frame, the communication nodes cannot transmit data because the allowed transmission data amount is “0”. Thereafter, when a management station in the network receives the token frame in which the allowed transmission data amount is set to 0, the management station transmits a token frame in which the allowed transmission data amount is set to “−1”. When the communication node that sets the allowed transmission data amount of the token frame received last time to “0” receives the token frame in which the allowed transmission data amount is set to “−1”, the communication node obtains a transmission right of data, sets the allowed transmission data amount to an initial value, and transmits data that could not be transmitted last time.
Patent Document 1: Japanese Patent No. 3487324